Exploring fluorine chemical evolution in the Galactic disk using GIARPS
Telescopio Nazionale Galileo (TNG) observed a sample of 14 stars belonging to the six open cluster (OCs) NGC 6939, NGC 7142, NGC 7762, Berkeley 32, Collinder 110, NGC 2429 and eight field stars, using the near-IR high resolution echelle spectrograph GIANO-B and HARPS-N (High Accuracy Radial velocity Planet Searcher in North hemisphere) in the GIARPS configuration. The objective of this study is to examine the correlation between fluorine (F) abundance and other variables, such as metallicity and age, across the Galactic disk to elucidate the origin of F by comparing observational data with Galactic chemical evolution models.
OCs are optimal tools for investigating the abundances of different elements, as their stars are expected to exhibit similar characteristics, including age, distance, and metallicity. Consequently, they serve as an effective means of investigating the cosmic origins of elements.
Thanks to the spectra taken with GIARPS it was possible to ascertain the abundance of fluorine, magnesium (Mg) and the slow neutron capture element cerium (Ce). In particular Mg abundances were employed to categorize the field stars into high and low alpha disk populations and Ce abundances were determined with great precision to explain the interplay between F and s-process elements.
Stellar parameters were determined using OH, CN, and CO molecular lines and band heads, as well as Fe I lines in the H-band region. Two HF lines in the K band (λλ 2.28 and 2.33 μm), three K-band Mg I lines λλ 2.10, 2.11, and 2.15 µm), and two Ce II lines in the H band (λλ 1.66 and 1.71 μm) were employed to derive the abundances of F, Mg, and Ce, respectively.
These data identified the critical role of Asymptotic Giant Branch (AGB) and fast-rotating massive stars (whose rotation speed likely increases as metallicity decreases) in the F production, contributing significantly to the broader narrative of Galactic chemical evolution and deepening the understanding of the interplay between fluorine, metallicity, and age across the Galactic disk.
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